I have my Note 4 for 3 years. It generally doesn't lag. It went to Samsung because the screen died and they did a complimentary repair, very classy and decent of Samsung.
They didn't want to fix it at first because they couldn't read the sticker on the inside of the phone that has the IMEI address. I have no idea why they couldn't read it or i removed it because it was blank but I was able to get verification that it was my phone and what the IMEI address was through AT&T and I had to send it back to them and then they fixed it and it's really running really well.
I keep having to replace batteries and I'm getting them from Anker and Anker has really been great about it as they replace them for free when they belly in the middle so that you can spin the battery around on a flat surface.
I have 4 batteries so I rotate them. However, as nohoku said continual crashes aren't great for the phone, what about continual battery pulls?
Back to the batteries bellying, sometimes it is hard to close the back plate. As I said before Samsung didn't want to fix my phone without the ticket on the inside being readible, especially when the screen is dead. Then I realized when seeing the smudged IMEI
#on the ticket inside the other day, i reakized what was happening because of the bellying battery, it would rub out the printing. It was also causing reboots because the battery itself got bigger because it bellied, it lost direct contact with the inside contact points and rebooted.
So why is this happening? I have the phone on really bright and that really kills battery life and makes the phone hotter and often times I don't even realize it but location devices is on and that really makes the phone hot. So I think those two factors are causing batteries to belly and maybe even in the case of the Note 7, where there is no place to expand to, explode.
Other than the battery issue, I don't see any reason why I would want to spend $1,000 to get a Note 8 that will give me what more than I have from the Note 4? Plus I need a new case and the tax and screen protector which I hear is $50. I just don't see the point. Samsung is,offering $400 off on your prior phone but they stopped it at the Note 5. I might have considered it with that discount but even so I'm talking about $600 plus I'm giving up my backup phone that's got to be worth $100 and then I need new stuff so that's another $75 so I'm still almost $800 and I'm not sure that it's worth it for a little bit better camera.
There is no substantial lag time on the Note 4 and I'm running 6.0.1 so what else am I going to gain for that much money?
Then I would also need $200 insurance because my Note 4 would be gone and all I have left is the Note 2.
For now I'm sticking with the Note 4.